A fiber mat was developed to visually determine the oxidation of edible oils, based on the colorimetric reaction of Schiff’s reagent and aldehydes - the major volatile formed during lipid oxidation. The mixtures of polyvinyl alcohol (PVA) and Schiff’s reagent containing various amounts of glycerol were electrospun to form the fiber mats. The response of the PVA/Schiff’s reagent fiber mats to gaseous hexanal (model aldehyde) was investigated. Oxidized soybean oils were used to evaluate the effectiveness of the PVA/Schiff’s reagent fiber mat for indicating oxidation of the oils. The results showed that the fiber mats obtained had average fiber diameters of less than 100 nm. Upon hexanal exposure, the fiber mats turned from white to purple. Higher amount of glycerol led to larger color change of the fiber mats and shorter response time to hexanal. A linear relationship ( R 2 = 0.96) was observed between the color change of the mat and hexanal concentration (15–117 μmol L −1 ). The visual determination limit of the mat for hexanal was 29 μmol L −1 . The color change of the PVA/Schiff’s reagent fiber mat was increased with an increase of soybean oil oxidation. Out of the seven soybean oils tested, the PVA/Schiff’s reagent fiber mat was able to correctly indicate the oxidation states of six oils. The result suggested that the visual determination method developed is a promising method to indicate the oxidation of edible oils, which can be performed easily by non-experts. Graphical abstract
Lipid oxidation is a big contributor to food deterioration. The objective of this study was to develop an intelligent film for visually detecting lipid oxidation, based on the colorimetric reaction of Schiff’s reagent and aldehydes—the major volatile lipid oxidation products. A polyvinyl alcohol (PVA) film containing Schiff’s reagent was formed, with the elasticity modulus of 0.27 MPa and the tensile strength of 19.17 MPa. The PVA film was exposed to various concentration (0–7.02 mg/L) of gaseous hexanal—the major aldehyde formed during lipid oxidation, the color change of the PVA film was measured by CIELab scale. The color of PVA film changed from colorless to purple after exposure to hexanal. As the hexanal concentration increased, the color change of the PVA film was more obvious. A linear relationship was found between the hexanal concentration and the color change. The developed PVA film could be an indicator for lipid oxidation of food when incorporated as a minor component of food packaging.
危险品化学品经营许可证（带存储）